This project addresses statistical problems generated from collaboration with scientists in other program areas and general statistical problems of current interest. This project is a continuing activity of the Section on Mathematical Statistics. Papers have been submitted or published in FY '87 on the following statistical subjects: pooled adjacent violators; general test of trend for count data; hypothesis tests involving linear inequality constraints; sampling strategies for rare diseases; the development of robust selection procedures based on vector ranks; the evaluation of sample size and power for analysis of survival with allowance for nonuniform patient entry, losses to follow-up noncompliance and stratification; stochastic curtailing for comparison of slopes in longitudinal studies; and selection criteria for use of the Kaplan-Meier or MLE for life table analysis. Other work in progress includes: statistics for the evaluation of space- time clustering of disease; adjustments for covariates in the analysis of categorical data; the influence of missing data on statistical models determined by variable on case-control studies; the use of area surveys in epidemiological research; the impact of risk and incidence of risk on selection of variables in multiple regression; the development of methods to improve coverage in surveys; the use of nonparametric tests for umbrella type with time dependent covariates; the development of methods of survival analysis for dependent competing risks; derivation of inferential methods for determining order of categorical data; comparison of common parametric and nonparametric survival analysis in the presence of mismodeling.